GB2251332A

GB2251332A - Searched program picture locking circuit

Info

Publication number: GB2251332A
Application number: GB9117843A
Authority: GB
Inventors: Se Young Jung
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 1990-12-31
Filing date: 1991-08-19
Publication date: 1992-07-01
Also published as: GB9117843D0; JPH05342820A; KR920013357A; DE4127416A1; DE4127416C2

Abstract

A searched program picture locking circuit for a video tape recorder having a video index search system comprising a VISS pulse delaying section 80 for prolonging index pulse signals, picture memory means 60 for storing a frame of a picture at the beginning of a program and an output selector 20 enabling the stored frame to be displayed between index signals. Means are also provided for causing the motor of the recorder to run at normal playing speed during the period of the prolonged index pulse signal and at fast-forward or rewind speed in the interval between subsequent prolonged index signals. <IMAGE>

Description

2251332 1 SEARCHED PROGRAM PICTURE LOCKING CIRCUIT The present invention

relates to a searched program picture locking circuit for use in a VTR (Video Cassette Tape Recorder) of the kind provided with a video index search system (hereinafter called 11VISS11). The invention relates particularly to a searched program picture locking circuit for use when searching programs on a video tape, whereby a regenerated picture which occurs at the beginning of a program can be displayed as a still picture until the next program on the tape is reached, after which a picture from that program appears.

It is known to provide a VISS function in a VTR for rapidly searching for desired programs, from among the many programs recorded on a tape. There are many different known kinds of VTRs having a VISS function. However, the VISS function is generally performed such that a regenerated portion of a program is displayed for about 5 seconds, after which the machine executes fast forward or rewind to search for the next index mark on the tape, after which a regenerated portion of the next program is again displayed for about 5 seconds. However, during the time between the first and next 5 second display periods, nothing is displayed on the television screen.

Therefore, whilst the tape is being rewound or wound fast forward, the user cannot see any thing at all, and 2 therefore, the contents of the program cannot be checked. This also tends to make the user become bored.

The present invention is intended to overcome these disadvantages of the prior art.

Therefore it is the object of the present invention to provide a searched program picture locking circuit for use in searching programs on video tape, in which the conventional problem of the lack of any picture during the period between display of the beginnings of sequentially searched programs is overcome. This lack of display is avoided by displaying a still picture from the beginning of the current program until the next program is detected.

Thus, a first aspect of the present invention provides a searched program picture locking circuit for a video tape recorder having a video index search system capable of locating programs recorded on a video tape by detecting index markers also recorded onto the tape, the locking circuit comprising:

an index marker detector for producing an index pulse signal for the duration of a detected index marker; a delay circuit connected to the index marker detector for producing a prolonged index pulse signal of a duration longer than the index pulse signal; a memory for recording a frame of a picture detected from the tape during the period of the prolonged index pulse signal; and 3 a selector enabling the picture frame stored in the memory to be displayed in the interval between subsequent prolonged index pulse signals.

A second aspect of the present invention is characterized in that in the VTR comprising a video signal regenerator for processing video signals detected by means of a video head before outputting them to a video output terminal; a VISS signal detector for transforming into pulses the VISS signals detected by means of a control head; and a motor control section for controlling the driving of a capstan motor by means of the pulses of the VISS signal detector, thereby performing a VISS function, searched picture locking circuit invention further includes: a delaying section for delaying during a certain period of time the pulse signals of the VISS signal detector; a picture memory means for enabling recording and reading the regenerating video signals of the video signal regenerator in accordance with the delayed pulses of the VISS pulse delaying section; and an output selector for selecting and outputting the signals read from the picture memory means and the output signals of the video signal regenerator in accordance with the delayed pulses of the VISS pulse delaying section.

The manner in which the above object is achieved, as well as other advantages of the present invention will become more apparent by reference to the following 4 description of a preferred embodiment of the present invention, and with reference to the accompanying drawings, in which:.

Figure 1 illustrates a searched program picture locking circuit according to the present invention; and Figures 2A to 2E illustrate operational timings and waveforms for sections of the circuit shown in Figure 1.

As shown in Figure 1, a video signal regeneration circuit 10 is connected to a first video head CH1, so. that the video signals extracted from a tape T by the first head are converted into standard analogue video signals.

A VISS detector 70 is connected to a second control head CH2, so that VISS index marker signals picked up by the second head are converted to electronic pulse signals. A VISS pulse delaying section 80 is connected to the VISS signal detector 70, so that the trailing edges of the pulses output by the latter are delayed for a certain period of time.

A motor control section 90 is connected to the VISS pulse delaying section 80 to enable the motor control section 90 to be controlled by the output pulses from VISS signal detector 70.

An analogue-to-digital converter 50 for converting the regenerated analogue video signals to digital signals is connected to the video signal regenerator 10. A picture memory section 60 is connected to the 0 VISS pulse delaying section 80, to the motor control section 90 and to the analogue-to-digital converter 50. This enable.s the digi.tal signals output by the analogue -to- digital converter 50 to be stored under the control of the VISS pulse delaying section 80, so that they can be readout in response to clock signals CLK.

A digital-to-analogue converter 55 is connected to the picture memory section 60, so that the output signals of the picture memory section 60 can be converted to analogue signals.

An output selector 20 is connected to the video signal regenerator 10 and to the digital-to-analogue converter 55 for selecting either the output signals of the digital-to-analogue converter 55 or the regenerated video signals from the regenerator 10 in response to the delayed pulses of the VISS pulse delaying section 80.

Reference code 40 indicates a television monitor or similar and 100 indicates a capstan motor of the VTR deck.

Figure 2 illustrates the operation of the picture locking circuit by means of the waveforms of different sections of the circuit.

The VISS index marker signals are recorded during an initial period of each program recorded on the tape. The index signals are detected by the control head CH2, and are supplied to the VISS signal detector 70. When an index mark is detected, the VISS signal detector 6 outputs a high-level VISS pulse for the duration of the index mark, as shown in Figure 2(A).

The VIS-S pulse signals from the VISS signal detector are then supplied to the VISS pulse delaying section 80. The latter circuit delays the trailing edge of the VISS pulse for a predetermined period of time as shown in Figure 2B before outputting them. In this way, the duration of each VISS pulse is prolonged, beyond the duration of its originating VISS index mark. The high level segment (a) of the delayed VISS pulse can be regarded as a regeneration period, while the low level segment (b) is a rewind or fast forward period.

During the high level period of the delayed VISS pulse, the video signals recorded on the tape T are picked up by the first video head CH1 and are processed by the video signal regenerator 10 to form regenerated analogue video signals. These analogue signals are supplied to a terminal 1 of the output selector 20, and also to the analogue-to-digital converter 50 to be converted into digital form so as to be recorded in the picture memory section 60.

The capacity of the picture memory section 60 is only required to be sufficient for recording one picture frame. The recording and reading operations performed by the picture memory section 60 are controlled by the delayed VISS pulses and by the clock pulses CLK.

The picture memory section 60 records one frame of the digital video signals from the analogue-to-digital 7 converter during the high level period (a) of the delayed VISS pulse. During the low level period (b) delayed pul.se (refer to Figure 2(C)), the digital video signals of the recorded one frame which are read out in response to the clock pulse CLK and are converted to analogue signals by the digital-to-analogue converter 55. The resulting analogue signals are then supplied to the terminal 2 of the output selector 20.

The position of the output selector is also controlled by the delayed VISS pulse of the VISS pulse. If the delayed VISS pulse is high level, the selector is switched to position 1 whilst if the delayed VISS pulse low, it is switched to position 2.

The video signals selected by the output selector 20 are supplied to the video output terminal 30 to be displayed on an external TV monitor.

Meanwhile, the motor control section 90 which controls the operation of the capstan motor 100 is always controlled by the delayed VISS pulses. If the delayed VISS pulse is high, the motor control section 90 causes the capstan motor 100 to run at normal playing speed so that video signals on the tape can be regenerated for storage in digital form. However, when the delayed VISS pulse is in the low state, the capstan motor 100 is caused to run at high speed for fast-forward or rewind. Thus, during VISS mode operation, during the period of the delayed VISS pulse, the video signal regenerator 10 outputs regenerated 8 video signals and the capstan motor runs at normal playing speed. At the same time, the output selector 20 is switched.to position 1, and the picture memory section 60 records a single frame of a picture at the beginning of a program in digital form.

Whilst the output selector 20 is switched to position 1, the video signals currently being regenerated are displayed on the TV monitor. However, when the delayed VISS pulse drops to a low level, the final picture of one frame will already have been stored in the picture memory section.

During the low level period of the delayed VISS pulse, the motor control section 90 makes the capstan motor run at high speed and the output selector is switched to position 2 so the the stored single frame of the'picture continues to be displayed as a still picture.

Thus, when the delayed VISS pulse drops to a low level, the picture memory section 60 stops the recording operation, and resumes the reading operation in response to the clock pulse CLK. Then, the digital signals which are read from the.picture data memory section 60 are supplied through the digital-to-analogue converter 55 and the terminal 2 of the output selector 20 as described above.

In this state, if VISS marker signals are again detected at the starting portion of the next program, the delayed VISS pulse signal again shifts to a high level. Then, the operations of the motor control 9 section 90, the output selector 20 and the picture memory section 60 are again controlled by the delayed VISS pulse,-making it-possible to see a regenerated picture at the start of that program. Then, a final frame of this new picture is recorded in the picture memory section 60 in place of the frame from the beginning of the previous program.

Thus, when searching a desired program using the VISS function, the final frame of a picture last regenerated at the beginning of the program being wound through is displayed as a still picture until the starting portion of the next program is found. This enables the user to be able continuously to recognize programs being searched.

Since a conventional digital VTR is already provided with a memory for storing a picture, the present invention can be applied to such a conventional machine in a simple manner. Moreover, it can easily be incorporated into a conventional analogue VTR, by adding a memory chip for picture storage.

According to the present invention as described above, the VISS function is used in such a manner that the final picture of the last program encountered during search can be kept displayed in the form of a still picture until the start of the next program, found by the VISS function. This has the additional advantage that the user using VISS to search through programs on the tape is less likely to become bored.

Claims

1. A searched program picture locking circuit for a video tape recorder having a video index search system capable of locating programs recorded on a video tape by detecting index markers also recorded onto the tape, the locking circuit comprising:

an index marker detector for producing an index pulse signal for the duration of a detected index marker; a delay circuit connected to the index marker detector for producing a prolonged index pulse signal of a duration longer than the index pulse signal; a memory for recording a frame of a picture detected from the tape during the period of the prolonged index pulse signal; and a selector enabling the picture frame stored in the memory to be displayed in the interval between subsequent prolonged index pulse signals.

2. A locking circuit according to Claim 1, further comprising means for causing a motor of the video tape recorder to run at normal playing speed during the period of the prolonged index pulse signal and for causing the motor to run at fast-forward or -rewind speed in the interval between subsequent prolonged index signals.

3. A searched picture locking circuit for use in searching pictures in a video cassette tape recorder capable of performing-VISS functions, comprising a video signal regenerator for processing video signals detected by a video head and for supplying the processed signals to a video output terminal a VISS signal detector for converting signals VISS signals detected by a control head CH2 to pulse, and a motor control section for controlling a capstan motor in accordance with the pulse signals of said VISS signal detector, the improvement further comprising:

a.VISS pulse delaying section for delaying the pulse signals of said VISS signal detector for a predetermined period of time; picture memory means for recording and reading video signals regenerated by said video signal regenerator in accordance with the delayed pulses signals of said VISS pulse delaying section; and an output selector for selecting and outputting the signals read by said memory means and the signals outputted from said video signal regenerator in accordance with the delayed pulse signals of said VISS pulse delaying section.

4. The searched picture locking circuit for use in searching pictures according to Claim 3, wherein said picture memory means comprises:

1 12 an analogue-to-digital converter for converting the regenerated video signals of said video signal regenerator.to digita signals; a picture memory section for recording and reading the digital signals of said analogue-to-digital converter in accordance with the delayed pulses of said VISS pulse delaying section; and a digital-to-analogue converter for converting the read signals of said picture memory section to analogue signals, to apply them to said output put selector 20.

5. A searched program picture locking circuit for a video tape recorder, the locking circuit being substantially as hereinbefore described with reference to the accompanying drawings.